Problem with strncpy

osfreak

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#include<iostream>

using namespace std;
 
typedef struct mystruct {
 
    unsigned char uDirFlag;
 
    unsigned int uFileSize;
 
    char uFilename[255];

} teststruct;
 
int main()

{

    char *flatbuf;
 
    teststruct *a = (teststruct*)malloc(sizeof(teststruct));
 
    a->uDirFlag = '0';

    a->uFileSize = 55;
 
    strcpy(a->uFilename,"Test message");
 
    int k = sizeof(teststruct);
 
    flatbuf = (char*)malloc(k);
 
    memset(flatbuf,0,k);
 
    strncpy(flatbuf, (char *)a, k);       //strncpy fails to copy uFilename properly
 
    teststruct *b = (teststruct*)flatbuf;      // b has uFilename field all set to 0
 
    return 0;
 
}

b has its uFilename field set to 0.

Can anyone Pls explain me why the the character values in the struct(uFilename field) were not copied properly??

newb16

Becase unsigned int uFileSize has at least two bytes, and all except least significant are zero, and strncpy stops on it.

osfreak

Is there a way i can force strncpy to copy till the specified bytes?

or is there any other string copy function to do such an operation?

osfreak

I have got it working by using memcpy(),

If there is someother way pls let me know...

Thanks for your help :)

JosAH

Quote:

Originally Posted by osfreak

I have got it working by using memcpy(),

If there is someother way pls let me know...

Thanks for your help :)

You aren't copying a string so don't use any str* function. Use memcpy() or memmove() instead.

kind regards,

Jos

osfreak

Got it working... Thanks anyway...

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